car finance

I purchased a new car via wesbank in november 2014 my contract said my total monthly installments was to be R3100, till this day I'm paying R400 more. Today I went to another bank to get a loan and I was denied a loan because wesbank claim that I'm in arres with my payment and already placed me under bad credit status. I've been paying all my installments on time I even have the proof. When I called to inquer of what was happening an agent by the name Moses was very rude and condescending. He told me I must go to joburg at their head office because he is thinking I'm lying. If this is not sorted soon I am taking this further I curse the day I delt with this useless bank who don't care about their clients but their pockets.